Let a cold Toad be placed (gelidus ponatur Bufo) upon a woman's chest (foemineo pectore), like a baby (instar infantis) so that it might drink (ut bibat) cups of milk (lactea pocla). And let it grow (crescat et) through the emptied teats (vacuata per ubera) into a great swelling (in magnum tuber), and the woman, sickened (et mulier aegra) will abandon her life (vitam liquerit suam). In that way (inde) you will make for yourself (tibi facies) a noble medicine (medicamen nobile) which can drive out poison (virus quod fuget) from the human heart ( humano corde) and can remove plague (levetque luem).

This is a gruesome business, and Maier even seems rather appalled himself, as he notes in the commentary:

The death of the woman in the emblem reminds him of Cleopatra who placed serpents at her breasts (viperas mammis admovit) so that she would not be taken alive by her conquerors.

It turns out, though, that what this emblem is supposed to signify is the Toadstone, which you can read about at Wikipedia: Toadstone. Maier describes the Toadstone as a type of gold (hence the alchemical connection), a stone inside the Toad which exceeds the power of mineral gold:

So, this is the first bit of "animal medicine" that has made an appearance so far in Maier's book. I wonder if there will be more of this to come! I'm very interested in things like this, especially the Shamir. Given that the Shamir was connected by legend to King Solomon, perhaps it will make an appearance in the alchemical world too.

As for the toad sucking at the woman's breasts, this sounds more diabolical than alchemical, as the toad was one of the animals notorious as a familiar of witches.